Differential adjustment



' P 1942- c. G. KRONMILLER 2,280,959

DIFFERENTIAL ADJUS TMENT Filed Dec. '7, 1959 ,fifiumtor Curl G. Kronmillzr Gnome g the differential of operation. This is often comgages'in a seat 22 in the lever [8. The adjusti ing lever 24 is pivotally'mounted on the bracket end of the lever 24 is a roller 28 which engages Patented Apr. 28, 1942 UNITED STATES PATENT OFFICE 2,280,959 DIFFERENTIAL ADJUSTMENT Carl G. Kronmiller, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minna, a corporation of Delaware I Application December 7, 1939, Serial No. 308,005

12 Claims. (Cl. 200-83) The present invention relates broadly to difoi the lever 24 is connected to one end of a ferential adjustments and is directed more parspring 28, the other end of which is connected ticularly to a novel way of obtaining an adjustto the lever l8. able differential for operating mechanisms of It will thus be seen that the spring 28 opposes the self return type in which a greater force 5 rotation of the lever l8 due to the expansion of is required to actuate them than to maintain the bellows 20 and also holds the roller 20 in them in actuated position. v engagement with the surface of the cam l3. Ro-

In prior art devices of the above type it has tation of the adjusting dial I2 will cause a rotabeen necessary to adjust certain parts of the tion of cam l3 and a corresponding adjustment operating mechanism itself in order to adjust it of the tension of the sprin 28 whereby t e lows will be opposed by a force which is deplicated and inconvenient, especially where the pendent upo the position 03 t e adjusting l operating mechanism is completely enclosed in h S l ay therefore be calibrated in a protective casing, such, for example, as in the degrees to indicate the temperature at which the case of the unitary snap action switch disclosed lever I8 is rotated by the bellows 20. inthe copending application of Albert E. Baak, It is desired that the lever l8 be used to 0P- Serial No. 307,991, filed Decemb r 7, 1939 crate a control mechan sm of the self return type It is therefore one f the primar obj ct in which a greater force is required to actuate of my invention to provide a differential adjustthe mechanism than to maintain it in its act'ument for devices of the above type, which is inde- 2 ated position. Although h s invention is pp pendent of the operating mechanism and which Cable y mechanism of this typ for the c011- is readily accessible and easily made. venience of illustration, a snap action switch Another object of my invention is to provide Such as the One discussed n t e ccpending 1 F1 a differential adjustment which is applicable nication of Albert E. Baak, Serial No. 307,991 iiled versally to all devices of the above type and in December 7, 1939, has been shown at 30. The which no changes in the operating mechanisms snap action mechanism is comple ely cl d are required when the application is made. n a casing t ough w c an Operating D 3| These and other objects are readily apparent extends. In order to actuate this switch a predeas the following specification is read in the light termined force must be exerted o he p H d of the accompanying drawing, in which after the switch has been actuated this force Figure 1 is a front elevation of an automatic must be decreased to a predetermined lower value switching arrangement embodying my invention, in order to permit the switch to return to its and original position. v I

Figure 2 is a side elevation of the device shown A differential adjusting mechanism has been in Figure 1. provided on the lever I 8 for actuating" the switch 30,. The end of the arm 32 of the lever I8 is numeral ll indicates an insulating base upon bent at right angles to the rest of the lever and which the adjusting dial I2 is rotatably mounted; a hole 33 is formed therein to form a first stop The base of the dial is provided with a helical 34. A porticn of the end of leg 32 has been cam l3 and a friction element It is mounted at broken away in Figure 2 in order to more clearly its ends to the base by means of screws II and show the hole and stop. A- -leaf spring 35 is the hole IS in the friction element receives the connected at one end to a bracket 88 carried by cam I 3 so that the element bears against the the lever l8 and the other end 31 extends through face of the dial lz'and offers a certain amount of the hole 33 and is biased against the stop 34. A resistance to itsmovement so that the dial will screw 39 is adjustably positioned in the lever ll remain in its adjusted positions. form a second stopi'or the spring 35, The Base II also carriesa bracket II upon which screw 39 may be furnished with a dial 40 to inthe lever I8 is mounted by two hinge elements dicate its adjustment relative to the lever l8. ll. -A bellows 201s mounted onthe base H and The spring 35 is originally tensioned against the bellows is provided with a pin 2| which enthe stop 3! to have a force which is suflicient to hold the switch 30 in actuated position but which is insufllcient to actuate the switch. Therefore when the switch 30 is in its normal position and v M the bellows 20 is'expanded the spring 38 will enthe surface of the helical cam II.- The other end gage the stop 34 .as shown Referring now to the drawing the reference 2| which is in turn carried by the base. At one inj lzure 2 of the drawing.. On a decrease in the spring 35 will engage adjusting dial l2 whereas the diiierenc tween two positions or tuate it in one its original position, a

spring lows 20' will contract and the spring 28 will move the lever l8 toward the switch 30. As it does so the pin II but as it does not exert a sufllcient force to actuate the switch 30 it will be flexed until it engages the stop 99. Further movement of the lever ll toward the switch will now actuate the switch. On an expansion or the, bellows 20 due to a temperature increase the lever 19 will move away from the switch iill but as the spring 35 exerts a sumcient force to hold the switch in its actuated position the spring will leave the stop 39 and eventually engage the stop 34 the switch. 011 further movement of the lever l8 away from the switch end 31 of the spring 35 and permit the switch 30 to move to .its original position.

It will therefore be seen that it is the position of the stop which determines the temperature at which the switch moves from its actuated to its original position and stop 39 which determines the temperature at which the switch is moved to its actuated position. The temperature at which the switch is moved to its original position can therefore be indicated directly on the scale carried by the between this temperature and the temperature at which the switch is moved to its actuated position may be indicated on the dial 40 carried by the adjustable stop 39.

It is therefore clear that the differential adjustment disclosed in the .present application is one which may be applied universally to any opas the lever moves away from.

the stop 3| will pick up theit is the position of the temperature the belspring means 2,280,959 member sufilcient to hold said mechanism in actuated position but incapable or exerting 'a sumcient force to actuate it, ing'an additional force independently oifsaid to said actuating member tor actuating said mechanism and for acting on said erating mechanism which requires a first force to actuate it and a second smaller force to main- J tain it in actuated position and that the adjustment may be applied to such mechanisms with-.- out changing the mechanism in any way. Fur- I thermore the adjustment is one which is simple 1.- In a device of the character described, an

operating mechanism of the self return type in which a predetermined force is required to actuate it in one direction smaller force will prevent it from returning to its original position, a control device shifted beoperation by said mechanism, an actuating member for said mechanism, means applying an initial force to said member "actuating member, said spring means sufficient force to actuate said mechanism whereand a predetermined suflicient to hold said mechanism in actuated position'but incapable of exerting a sufilcient force to actuate it, and means rdr supplying an additional force independently of said last mentioned means toactuate said mechanism and then removing said additional force and someof said initial force to permit'said mechanism to return to its original position.

2. In a device of the, character described, an operating mechanism of the sell return type in which a predetermined force is required to acdirection and a predetermined smaller force will prevent it from returning to control device shifted between two positions or operation by said mechanism, an actuating member tor said mechanism,

means exerting a'iorce on said actuating spring means to remove some of the force which is required to actuated position but incapable of exerting a sufilcient force to actuate device, a control supplying an additional force to said actuating member independently of said spring means for actuating said mechanism at one condition value and for acting on said spring means at a second condition value to remove some of the force which it exerts on said actuating member in order to permit. said mechanism to return to its original it, a condition responsive position, and means for varying thedifierence between said condition values.

4. In a device of the character described, an operating mechanism of the self return type in which a predetermined force is required to actuate it in one direction and a predetermined smaller force will prevent it from returning to its original position,. a control device shifted between two positions of operation by said mechanism, an actuating member for said mechanism, a control member, first and second stops on said control member, spring means carried by said control member, said spring means being biased against said first stop, and a condition responsive device for moving said control member in a direction to cause said spring means to engage said having inby it is flexed into engagement with said second stop so as to tinued movementof said control member, said spring means having sufficient force to maintain said mechanism in actuated position whereby said mechanism does not return to its original position until the spring means engages said first stop on a reverse movement of said control member.

) 5. In a. device ofthe character described, an operating mechanism of the self return type in which a predetermined force is requiredto actuate it in one direction and "a predetermined smaller force will prevent it from returning to its original position, a control device shifted between two positions of operation by said mechanism, an actuating member for said, mechanism, a control member, first and second member, spring means carried by said control member, said spring means being for moving said control member in a direction to cause said spring means to engage said actuatin member, said spring means having insuflicient force to actuate said mechanism whereby it is and means for supplythe self return type in membermovable thereby for actuate said mechanism on constops on said control biased against said first stop, and a condition responsive device.

having sufiicient force to maintain said mechanism actuated position whereby said mechanism does not return to its original position until the spring means engages said first stop on a reverse movement of said control member, one of said stops being adjustable to vary the differential of operation of said switch.

6. In a device of the character described, an operating mechanism of the self return type in which a predetermined force is required to actuate it in one direction and a predetermined smaller force will prevent it from returning to its original position, a control device shifted beand a condition responsive device for rotating said lever to cause said spring to engage said pin, said spring having insuiiicient force to actuate said switch whereby it is flexed into engagement with said second stop so that said switch is actuated on further rotation of said lever, said spring exerting suflicient force to maintain said switch in actuated position wheretween two positions of operation by said mechanism, an actuating member for said mechanism, a control member, said control member having an offset portion in the form of a stop, a leaf spring fixed at one end to said control member, the free end of said spring being biased against said stop, a second stop adjustably carried by said control member, and a condition responsive device for moving said leaf spring in a direction to engage said actuating member, said leaf spring having insufiicient strength to actuate said mechanism whereby it is flexed until it engages said second stop resulting in actuation of said mechanism upon continued movement of said control memher, said spring having sufiicient strength to maintain said mechanism in actuated position whereby said mechanism cannot return to its original position until after said leaf spring is picked up by said first step on a reverse movement of said control member.

7. In a device of the character described, a snap action switch of the self return type, an actuating member for said switch, spring means exerting an initial force on said actuating member sufficient to hold said switch in actuated position but incapable of exerting a suilicient force to actuate it, and a condition responsive device for supplying additional forceindependently of said spring means to actuate said switch and for removing said additional force and some of said initial force to permit said switch to return to its original position.

8. In a device of the character described, a snap action switch of the self return type, a casing enclosing said switch, an actuating pin extending through said casing, a lever, a pair of stops carried by said lever, a leaf spring carried by said lever and biased against said first stop, and a condition responsive device for rotating said lever to cause said spring to. engage said pin, said spring having insufficient force to actuate said switch whereby it is flexed into engagement with said second stop so that said switch is actuated on further rotation of said lever, said spring exerting sufllcient force to maintain said switch in actuated position whereby said switch cannot return tov its original position on a reverse rotation of said lever until after said spring has been picked up by said second stop.

9. In a device of the character described, a snap action switch of the self return type, a

casing enclosing-said switch, an actuating pin extending through said casing, a lever, a pair of stops carried by. saidlever, a leaf spring carried by said lever and biased against said first stop by said switch cannot return to its original position ona reverse rotation of said lever until after said spring has been picked up by said second stop, one of said stops being adjustable to vary the difference in the condition values at which said switch is actuated in each direction.

10. In a device of the character described, an operating mechanism of the self return type in which a predetermined force is required to actuate it in one direction and .a predetermined smaller force will prevent it from returning to its original position, a control device shifted between two positions of operation by said mechanism, spring means for holding said mechanism in actuated posltion but incapable of developing a force great enough to actuate it, a condition responsive device, and connections between said condition responsive device and said mechanism, said connections including means for actuating said mechanism at one,v value of said condition and removing the effect of said spring means at another value of said condition, said actuating means actuating said mechanism independently of any spring force of said spring means.

11. In a device of the character described, an operating mechanism of the self return type in which a predetermined force is required to actuate it in one direction and a predetermined smaller force will prevent it from returning to its original position, a control device shifted between two positions of operation by said mechanism, a condition responsive device, and connections between said condition responsive device and mechanism for operating said mechanism at one value of said condition and permitting it to return at a second value of said condition, said connections including a spring for retaining said mechanism in actuated position and stop means for removing the effect of said spring.

12. In a device of the character described, an operating mechanismof the self return type in which a predetermined force is required to actuate it in one direction and a predetermined smaller force will prevent it from returning to its original position, a control device shifted between two positions of operation by said mechanism, a condition responsive device operatively connected to said mechanism, and means for determining the differential of operation including a spring which is capable of maintaining said mechanism in actuated position but is incapable of developing a force great enough to actuate it, and means for removing the eflect of said spring at a value of said condition, said t mentioned means actuating said mechanism independently of any spring force of said spring at a different value of said condition.

' CARL G. KRONMIILER. 

